Trends in reproductive success of Hawaiian seabirds: is guild membership agood criterion for choosing indicator species?

Because it is rarely possible to monitor all species that occur in sensitiv e or threatened ecosystems, much theoretical consideration has been given t o the process of choosing indicator species. We evaluated whether foraging guild classification or nest site might be an adequate means to select indi cator species for monitoring the reproductive success of a suite of Hawaiia n seabird species. We examined the reproductive success of six species repr esenting three foraging guilds and two types of nest sites over an 18-year period. For two of the three foraging guilds, there was a strong correlatio n between the reproductive success of birds from the same guild, and there was a weaker correlation for the third guild. In contrast, there were no si gnificant reproductive success correlations for pairs of species from diffe rent foraging guilds but with the same nest sites. Thus, the within-guild c orrelations are likely to be driven by guild-specific food availability rat her than by similarity in nest site. Because of the weak nature of one of t he within-guild correlations, and because there is little detailed informat ion on the causes of nest failure in this system, we recommend continuing t o monitor multiple indicator species per foraging guild. (C) 2001 Elsevier Science Ltd. All rights reserved.